Boulder Rez Marathon

Lace up for an unforgettable Colorado running experience at the Boulder Rez Marathon, set for August 15, 2026, in scenic Boulder, CO. This popular event offers a distance for every runner, including a full Marathon, a unique 19.7-mile 3/4 Marathon, Half Marathon, 10K, and a Marathon Relay. The course itself is a highlight, taking participants on a mostly flat journey around the picturesque Boulder Reservoir, predominantly on dirt roads and trails, with stunning views of the Rocky Mountains and the iconic Flatirons providing a breathtaking backdrop. While the course boasts minimal elevation gain, some gentle rollers add to the challenge, especially in later loops.

Typical race day conditions in mid-August feature average highs around 87°F and lows near 56°F, with a low chance of precipitation, meaning runners should be prepared for potential heat. Fortunately, the race is exceptionally well-supported with aid stations stocked with water and Gatorade, strategically placed around the looped course (marathoners will hit them multiple times) and staffed by enthusiastic volunteers ready to assist. Beyond the scenic and well-organized route, the Boulder Rez Marathon is known for its friendly atmosphere and lively post-race celebration, complete with music, awards, beer, and food.

The course starts and finishes at the Boulder Reservoir, making for easy logistics, and runners often appreciate the opportunity to set up personal aid stations along the accessible looped route. Whether you're chasing a personal best on the fast, USATF-sanctioned course or simply soaking in the incredible mountain vistas, the Boulder Rez Marathon promises a rewarding and memorable race experience.